1. Field of Invention
This invention relates to 2,5-bis(substituted aryl)thiazolo[5,4-d]thiazole compounds, and particularly to 2,5-bis(o-hydroxyaryl)thiazolo[5,4-d]thiazole color-formers, to their reactions with metal salts to form colored coordination compounds, and to imaging systems based thereon. The formation of colored coordination compounds can be employed to generate images and is important in the manufacture and use of pressure-sensitive transfer papers for preparing carbonless copies.
The invention also concerns the admixture of these color-formers with N-(monosubstituted)dithiooxamides and/or N,N'-(disubstituted)dithiooxamides to form images of various colors and preferably black images during the application of appropriate pressure to pressure-sensitive imaging constructions such as carbonless paper constructions.